/*
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.util.function;

import java.util.Objects;

/**
 * Represents a function that accepts two arguments and produces a result.
 * This is the two-arity specialization of {@link Function}.
 *
 * <p>This is a <a href="package-summary.html">functional interface</a>
 * whose functional method is {@link #apply(Object, Object)}.
 *
 * @param <T> the type of the first argument to the function
 * @param <U> the type of the second argument to the function
 * @param <R> the type of the result of the function
 * @see Function
 * @since 1.8
 */
@FunctionalInterface
public interface BiFunction<T, U, R> {

  /**
   * Applies this function to the given arguments.
   *
   * @param t the first function argument
   * @param u the second function argument
   * @return the function result
   */
  R apply(T t, U u);

  /**
   * Returns a composed function that first applies this function to
   * its input, and then applies the {@code after} function to the result.
   * If evaluation of either function throws an exception, it is relayed to
   * the caller of the composed function.
   *
   * @param <V> the type of output of the {@code after} function, and of the composed function
   * @param after the function to apply after this function is applied
   * @return a composed function that first applies this function and then applies the {@code after}
   * function
   * @throws NullPointerException if after is null
   */
  default <V> BiFunction<T, U, V> andThen(Function<? super R, ? extends V> after) {
    Objects.requireNonNull(after);
    return (T t, U u) -> after.apply(apply(t, u));
  }
}
